THE CLIMATE OF ECONOMIC CHANGE
Climate change and economic change are two major challenges facing the road surface sector. The 2010 RSTA annual conference, The Climate of Economic Change, examined how best to answer those challenges with cost-effective and long-term solutions.
The extreme weather patterns predicted to result from climate change can have a profound impact on roads. This was demonstrated by Andrew Warrington, highways manager for Leicestershire County Council, in his presentation, ‘Economic and Climate Change: Resilience for Local Highways’. Warrington underlined this with examples of the impact of extreme weather events over recent years. In 2006, there was the summer heat wave that damaged 80km of rural roads in Leicestershire costing £2 million. The floods of 2007 required £5 million for additional highway drainage works. 2008 saw the warmest May on record resulting in an extended growing season and increased expenditure on verge maintenance. Whilst, 2009 and 2010 saw the most severe winter for 30 years resulting in widespread road cracking and potholes. Warrington highlighted the need to undertake comprehensive transport asset management and risk assessment plans. These must ascertain life cycle and whole life costs, provide planned maintenance strategies, define service levels and monitor and review performance. These plans provide important tools for arguing the case for appropriate investment in roads.
Asking for and getting road funding is one thing ensuring that it is well spent is another. Warrington argued for greater cost economies and value for money. He forwarded the case for cost savings and efficiency improvements that resulted from greater collaboration between local authorities examples being the 3 Counties Alliance Partnership between Leicestershire, Nottinghamshire and Derbyshire County Councils and the Midlands Highway Alliance. Such collaboration encourages procurement efficiencies that result in real value for money and ensure that there is a widespread understanding of how to adapt to the predicted impacts of climate change together with an appreciation that preventive maintenance is economic good sense compared to the more expensive renewal and replacement.
The climate and economic challenges facing the national trunk road network were presented by Donna James, team leader for Pavement Design and Materials at the Highway Agency. She outlined how the Highways Agency seeks to be recognised as being the ‘world’s leading road operator’. Part of the achievement of this ambition is the management and reduction of carbon emissions relating to road surfaces. In particular, this includes the ethos ‘less is more’ with regards to the use of natural resources and energy. With this in mind, the Agency is seeking to achieve 25 per cent of pavement products responsibly sourced by 2012 together with a 50 per cent reduction in landfill and a 70 per cent recovery of non-hazardous waste. The Agency is seeking commitment from the supply chain to enable these targets to be reached.
As part of its sustainability strategy, the Highways Agency is also developing asPECT, an asphalt pavement embodied carbon tool. This will provide a methodology to calculate the life cycle and carbon footprint of asphalt used in highways and is being developed in collaboration with the Mineral Products Association, Refined Bitumen Association and TRL Limited with further endorsement by the Waste & Resources Action Programme and the County Surveyor’s Society. It is planned that the resultant carbon footprint calculator tool with be expanded to include other highway products. James highlighted the progress that has already been made within the highway sector, emphasising that the sector as an industry leader is proactively meeting the challenges that are posed by sustainability. James also called for closer collaboration between the Highways Agency and the road surface treatments industry to find ways of extending the use of surface treatments on the network.
The work by the Highways Agency on the development of a carbon footprint calculator tool is mirrored by that of the RSTA, who is funding a research project with the University of Nottingham to develop a carbon calculator tool for a range of road surface treatments used by road maintenance contractors. Outlining current progress, Dr Tony Parry, associate professor in the Nottingham Transportation Engineering Centre in the Department of Civil Engineering, University of Nottingham, explained that the demand for such a tool results from the National Authority National Indicator NI 185 that requires local authorities to calculate the carbon footprint of their buildings and services. This will require road maintenance contractors being asked to supply information on the carbon footprint of their products and operations. It is expected that the RSTA calculator will be integrated into the overall Highways Agency asPECT tool.
The calculator will not only enable RSTA members to ascertain the carbon footprints of their products and processes but will also allow the identification of carbon ‘hot spots’ where major reduction in carbon emissions can be made. Parry warned that the success of the tool is subject to the quality of data provided by RSTA members and called for their support and input.
The issue of cost effectively addressing the challenges of long term performance and sustainability was examined by Dougie Millar, materials and QA advisor for Transport Scotland. He explained the use of Crack and Seat which is a cost effective alternative to traditional solutions of a thick layer of asphalt or the removal of the concrete base. Crack and Seat involves ‘cracking’ the concrete slabs in-situ with a large guillotine and then ‘seating’ the slabs with a heavy roller after which a thin asphalt surface course is applied. The new cracks will accommodate some of the thermal movement and the new surface will not deteriorate at an accelerated rate. Crack and Seat can thus extend the strength of the structural layer. Energy consumption, the use of aggregates and the amount of material taken to landfill are all reduced compared to traditional reconstruction. Millar reviewed the benefits of using dense German SMA (stone mastic asphalt) surface course mix designs on Scottish roads and argued for skidding resistance to be actually measured in service rather than relying on specifying a minimum texture depth.
Millar also highlighted the use of EME2. EME2 (enrobe a module) is a high strength, long-life asphalt base and binder course material developed in France that provides high levels of workability and impermeability plus greater resistance to cracking and deformation. The smaller nominal aggregate size used and the increased binder content provides the level of toughness necessary for long-life pavement designs. Designing durable asphalt roads using EME2 bases and SMA surface course,only replacing the surface course when it wears out and never having to replace the lower layers, is the cornerstone of Transport Scotland’s sustainability strategy explained Millar
A common theme throughout the conference was the role that the road surface treatments sector itself can play by working with clients to develop solutions that are innovative, cost effective and sustainable. The sector has risen to the challenges posed by climate and economic change. It is investing in new products and processes and is ready to collaborate and share best practice in order to provide ‘more for less’ and ‘less is more’ in terms of meeting budget restrictions and delivering carbon emission reductions.